Gaseous electric discharge device



Nov. 8, 1938. w. HAGEN ET AL GASEOUS ELECTRIC DISCHARGE DEVICE FiledJan. ll, 1937 5 a 7 3 w il -"2312!! 2 o n v g m ?IVII,AVIIIW4FIIII/ICEC2i 0 F i e nr 2 aln mHTjm m 26R N mn W/ E V O A m g .hm fl o WWmPatented Nov. 8, 1938 UNITED STATES PATENT OFFICE Berlin-Wilmersdorf,Germany,

assignors to General Electric Company, a corporation of New YorkApplication January 11, 1937, Serial No. 120,066 In Germany January 15,1936 1 Claim.

' The present invention relates to gaseous electric discharge devicesgenerally and more particularly the invention relates to vapor dischargelamp devices operating with elevated container 5 temperatures and withcorrespondingly elevated vapor pressures, such as a vapor pressure inthe order of atmospheres, similar to those disclosed in co-pendingapplication, Serial No. 4,312, filed October 6, 1936, the inventorsbeing Marcello 10 Pirani, Robert Rompe and Wolfgang Thouret.

The gaseous electric discharge lamp devices disclosed in the co-pendingapplication referred to above comprise a pair of electrodes centrallymounted in an elongated container and separated a distance less than thediameter of the container.

The current leads supporting the electrodes extend a substantialdistance into the container, and consist of high melting point materialsuch as tungsten or molybdenum. The container is of small size andconsists of a vitreous material, such as fused silica, capable ofwithstanding the high temperatures. Due to the different coeflicients ofexpansion of the vitreous material and the metal it is desirable to usegraded seals for such devices.

The object of the present inventionis to provide a gaseous electricdischarge lamp device of the above type which comprises means of simplestructure for protecting the part of the current leads inside the lampcontainer from the efiects' of the gaseous electric discharge. Anotherob- Ject of the invention is to provide a gaseous electric dischargelamp device of the above type which is simple in structure and isinexpensive to manufacture. Still further objects and ad vantagesattaching to the device and to its use and operation will be apparent tothose skilled in the art from the following particular description.

The invention attains its objects by surround- 4() ing the internal partof the current'lead with a tube or sleeve of high heat resisting,insulating material, such as quartz, the internal diameter of whichclosely approaches the diameter of the current lead extendingtherethrough to insure protection of the current lead from the gaseouselectric discharge. The lead protecting sleeve is part of the stemstructure of the lamp which stem consists of the aforesaid sleeve, agraded joint fused to the end of and hermetically closing the end ofsaid sleeve and a current lead fused into said joint and extendingthrough and beyond said sleeve. In the manufacture of the device thestem structure is first fabricated and the sleeve is then fused to thecontainer to make an hermetic joint therein. The sleeve extends asubstantial distance into the container and terminates ad- J'acent theelectrode mounted on the end of the current lead.

We have observed that no diminution in the quantity of vaporizablematerial available for 5 the discharge takes place in a gaseouselectri'c. discharge lamp'device embodying the present invention evenafter the device has been operating for several hundred hours. In manycases this is of importance, for example, when a limited 10 quantity ofmerc1u-y is introduced into the lamp during the manufacture thereof inorder to vobtain an unsaturated vapor pressure when the lamp is atoperating equilibrium. Any loss in the quantity of vaporizable materialin the dis- 15 charge chamber of a device so constructed would, ofcourse, change the electrical characteristics of the device, which isundesirable. While this is apt to be a source of difficulty in deviceshaving protruding seals it does not take place in 20 devices embodyingthe present invention due to the fact that the electrode is closer tothe end of the insulating sleeve than to the end of the container andconsequently the end of the sleeve is at a higher temperature during theoperation of the 25 device than the end of the container. Anycondensation of mercury vapor therefore takes place at the end of thecontainer where it is available for the discharge rather than inthe,sleeve where it is not available for the discharge. 30

In the drawing accompanying and forming part of this specification agaseous electric discharge lamp device embodying the invention is shown.in which Fig, 1 is a side elevational view of a. gaseous elec- 35 tricdischarge lamp device, and

Fig. 2 is a sectional view of one end of the lamp shown in Fig. 1.

Referring to the drawing the gaseous electric discharge lamp devicecomprises an elongated, 40 tubular, quartz container I having a pair ofcurrent leads 4 sealed therein, one at each end thereof. Said currentleads 4 consist of a high melting point material, such as tungsten. Saidcontainer i has therein a starting gas, such as argon, and a quantity ofvaporizable material, such as mercury, the vapor of which is luminosityproducing during the operation of the device. An electrode 5 is mountedon each of said leads 4. Each of said electrodes 5 consists of aperforated, tungsten shell filled with a mixture of electron emittingmaterials, suchas a mixture of aluminum oxide, tungsten and an alkalineearth oxide. Said electrodes 5 are heated to an electron emittingtemperature during the operation of the device by the discharge.

Said container i has a stem at each end thereof which stem consists of aquartz tube 2, 1, a graded seal 8, 9, I0, H .fused to the end of saidtube 2, I and to said current lead 4. The part 8 of said seal 8, 9, Ni,ii fused to said lead 4 consists of a glass having a coefficient ofexpansion approximating that of the tungsten lead 4 and the part II ofsaid graded seal 8, 9, III, II consists of a glass having a coefficientof expansion approximating that of the quartz tube 2, I. Theintermediate parts 9 and ID of the seal have coefiicients of expansionintermediate those of the parts 8 and H. The part I of said tube 2, 1extends from the endof said container I to a point adjacent theelectrode 5 and has an opening 8 therein which is but slightly larger indiameter than the current lead 4 extending through said part 1. The part2 of said tube 2, 1 extends a short distance beyond the end of thecontainer I and has an opening 3 therein having the same diameter as thepart 6 of the opening.

In the manufacture of the lamp device described above the stemconsisting of the tube 2, 1, the seal 8, 9, [8, H, the current lead 4and the electrode 5 is first fabricated and the end of the container lis then fused to the'tube 2, l. The other steps in the manufacture ofthe lamp device, such as the treatment of the electrodes, exhausting thecontainer and introducing the starting gas and the vaporizable materialinto the container; are then carried out.

The advantages of a gaseous electric discharge lamp device having theabove structure have been pointed out above. It will be understood, ofcourse, that numerous changes in the form and details of the deviceillustrated may be made within the scope of the appended claim, forexample, the tube 2, I is wholly within the container I when desired.

What we claim as new and desire to secure by Letters Patent of theUnited States is:

A gaseous electric discharge device comprising a vitreous container,electrodes and electrode leads sealed therein, a gaseous atmospheretherein, said container having a stem comprising an elongated tube ofvitreous material fused thereto, said tube surrounding one or saidcurrent leads and extending a substantial distance into said container,the coefiicient of expansion of said tube being approximately equal tothat of said container and being difierent than that of said currentlead, the inner diameter of said tube being slightly larger than thediameter of said current lead, the external end of said tube beingclosed by a graded seal fused thereto and to said current lead, saidcurrent lead extending along said tube and projecting beyond theinternal end thereof, one of said electrodes being mounted on saidcurrent lead and adjacent the inner open end of said tube.

WILHELM HAGEN. WOLFGANG THOURET.

